Safety joint



SAFETY JOINT Filed June 1, 1945 gvwam co y 'FI- 14% @5462 y PatentedFeb. 8, 1 949 ETED STATES PATENT; OFFICE SAFETY JOINT Walter L. Church,H gan, Tex h Application June 1, 1945, Serial No. 597,009

This invention relates to a safety joint.

An object of the invention is to provide-a safety joint adapted tobeconnected-into a string of pipe which string is made up of sectionsconnected together by threads and the safety joint, in the string, is ofsuch construction that it may be more easily unscrewed than the otherthreaded connections of the string.

In carrying on operations in a well the drill stem, or other string ofpipe in the well, sometimes becomes stuck so that it cannot be withdrawnand must be unscrewed and separated in order to recover as much of thestring as possible. For example, the drill at the lower end of the drillstem may become stuck in the well bore; or a well packer on a string ofwell pipe may become stuck so that it cannot be released. In such casewith the safety joint herein described incorporated into the drill stemabove the drill or incorporated into the string of pipe above the packerthe rotation of the drill stem, or string of pip reversely will causethe safety joint herein described to separate, without danger ofunscrewing one of the threaded connections above, so that the majorportion of the stem or string can be recovered.

It is another object of the invention to provide a safety joint of thecharacter described which will not be liable to unscrew and cause thedrill stem, or string of pipe, to separate while the same is beinglowered into the well.

With the above and other objects in view the invention has particularrelation to certain novel features Of construction, arrangement of partsand use, an example of which is given in this specification andillustrated in the accompanying drawings, wherein:

Figure 1 is a side view of the safety joint partly in section.

Figure 2 is a cross sectional view taken on the line 2-2 of Figure 1;and

Figure 3 is a side elevation of the p member- In the drawings thenumeral I designates the box member of the joint which is formed with anoutwardly threaded pin 2, at one end, adapted to be screwed into theadjacent end of the section of drill stem, or tubular string, beneath.This box member has the internal coarse threads 3 and the internal blankportions 4 and 5 above and beneath said threads, the blank portion 4being flush with the base of the threads and the blank portion 5 beingflush with the crests of the threads. The numeral '6 designates the pinmember, both the box member and pin member being tubular.

The pin member has the coarse, external threads i adapted to intermeshwith the threads 1 Claim. (01. 2875125) 3 when the pin member is screwedinto home position in the box member. The pin member has a, blankportion 8 beyond the threads and countersunkinto this blank portionthere is an annular packing 9 which fits closely with the portion 5. Thepin member has perforations l0 leading outwardly therethrough oppositethe packing 9 whereby fluid flowing under pressure through the safetyjoint may operate against the packing 9 to hold it closely against theblank p rtion 5 of the box member.

On the opposite side of the thread I the pin member has the blankportion I l which fits snugly within the blank portion 4 of the boxmember.

Countersunk into this blank portion of the pin member are the elongatedfriction members l2 which are seated on coil springs [3 whereby thefriction members are held outwardly into frictional engagement with theblank portion 4 of the box member.

The friction members I2 are retained in place by the end set screws I4,4 which are screwed into the pin member and against'the heads of whichthe ends of the friction members engage.

The pin member has the external, cam shaped, end faces l5, l5 which arecorrespondingly pitched and terminate in the abrupt shoulders l6 whichare adapted to engage with opposing shoulder IT on the confronting endof the box member I, when the pin member is screwed to home position.These interengaging shoulders l6 and I1 take the torsional strain towhich the drill stem is subjected while drilling or to which the stringof P p is subjected when it is turned to the right so as to prevent thepin member from becoming screwed too tightly in the box member.

The friction members l2 frictionally engage the inside of the boxmember, as shown in Figure 1, so that the string of drill stem, or pipe,beneath will be held against unscrewing while going into the well.

Itis to be noted that the upper end of the pin member has an internallythreaded box I8 for connection to the string of drill stem, or pipe,above.

However, if the drill stem beneath the safety joint should become stuckin the bore so that it cannot be pulled out the drill stem may berotated to the left and the pin member 6 screwed out of, and separatedfrom, the box member I and the string of drill stem above then recoveredfrom the bore; or if the string of pipe should be used in settling apacker in the well, or for carrying on fishing operations, withthesafety joint herein described incorporated therein, above the packer,or fishing tool, should the packer, or tool, become stuck the string maybe turned to the left and the safety joint separated, as aboveexplained, and the string of pipe thus recovered. In either case thedrill stem or string of pipe will be separated at the safety joint andnot at some other coupling for the reason that the connecting threadsthereof will be intermeshed loosely; however, said threads will notbewpermitted tobecome unscrewed, while going into the Well, by. reasonof the frictional engagement of the friction members 12 with theinternal blank portion 1 4 of the box member 1. i

The invention herein described includes certain.

improvements over that type of pipejoint dis; closed in United StatesPatent No. 2,075,427 issued to applicant on March 30, 1937:.

The drawings and description are illustrative merely while the broadprinciple of the invention will be defined by the appended claim.

What I claini is:

A safety joint comprising, a box section having internal threadsandjbeing internally blank betwenthe threads and the end of "thesection, a

REFERENCES CITED The following reierences are of record in the file, oithis, patent:

, rnp, STATES PATENTS Ninnber Name Date 1,701,985 Ponto Feb. 12, 19291,806,059 Hoopla May 19, 1931 2,049,289 Burnsetal. L -1 July 28, 19362,112,108 Mackenzie MarQ22, 1938 2,113,321- Baash Apr. 12, 1938'

